Experimental and theoretical study of demagnetization fields in superconducting samples of orthorhombic shape

In this work we present a model for the calculation of the magnetic properties of superconductors of orthorhombic shape in the perfect shielding state when an external uniform magnetic field is applied in the direction of one of the principal axes of the sample. Our model accounts for demagnetization effects and it is free of fitting parameters and boundary value conditions. We consider planar linear circuits that lie perpendicular to the direction of the applied field. Calculation of the value of the currents is based on magnetic energy minimization. The model is proved to be accurate enough to reproduce experimental results as long as the dimension along the applied field is not much lower than the other dimensions. Calculations of surface currents, as well as measurements and calculations of magnetization and initial susceptibility, are reported. We also present an empirical formula that provides a good fit to the initial susceptibility of a general sample of orthorhombic shape. Demagnetization effects observed on the experimental results are explained in terms of the induced currents in the superconductor. (C) 2004 American Institute of Physics.96148649

Central and peripheral GLP-1 systems independently suppress eating

The anorexigenic peptide glucagon-like peptide-1 (GLP-1) is secreted from gut enteroendocrine cells and brain preproglucagon (PPG) neurons, which, respectively, define the peripheral and central GLP-1 systems. PPG neurons in the nucleus tractus solitarii (NTS) are widely assumed to link the peripheral and central GLP-1 systems in a unified gut–brain satiation circuit. However, direct evidence for this hypothesis is lacking, and the necessary circuitry remains to be demonstrated. Here we show that PPGNTS neurons encode satiation in mice, consistent with vagal signalling of gastrointestinal distension. However, PPGNTS neurons predominantly receive vagal input from oxytocin-receptor-expressing vagal neurons, rather than those expressing GLP-1 receptors. PPGNTS neurons are not necessary for eating suppression by GLP-1 receptor agonists, and concurrent PPGNTS neuron activation suppresses eating more potently than semaglutide alone. We conclude that central and peripheral GLP-1 systems suppress eating via independent gut–brain circuits, providing a rationale for pharmacological activation of PPGNTS neurons in combination with GLP-1 receptor agonists as an obesity treatment strategy

Structural and magnetic study of LaBaCoCuO5+delta

The structure and magnetic properties of the compound LaBaCuCoO5+delta have been studied for the non-stoichiometric oxygen concentration delta approximate to 0.6. The structure is pseudo-cubic with a tripled perovskite unit cell. The crystal structure was determined by a combined Rietveld fit to neutron and synchrotron x-ray powder diffraction data in the orthorhombic Pmmm space group, with cell parameters a=3.9223(3) angstrom, b=3.9360(3) angstrom, c=11.7073(8) angstrom, and V=180.74(2) angstrom(3) (room temperature). Antiferromagnetic ordering of Cu and Co magnetic moments is observed below 205(4) K. The magnetic structure with cell a(M)=2a, b(M)=2b, and c(M)=2c, could be described with the Shubnikov space group Fmmm'. The magnetic moments of both equivalent Cu/Co sites were determined at 50 and 170 K to be 0.83(3)mu(B) and 0.58(3)mu(B), respectively, consistent with one unpaired electron per atom. The fit of the intensities to a simple mean field magnetic model appeared to be insufficient to account for the variation of moments at temperatures close to T-N while a three dimensional Heisenberg model could improve the fit. Susceptibility measurements between 4 and 350 K also show irreversibility below 150 K. The local environments of Cu and Co were studied by extended x-ray absorption fine structure spectroscopy at both absorption edges. Cu atoms adopt an elongated octahedral or square-based pyramidal oxygen environment which suggests mainly the presence of Cu(II) in the structure. Co adopts different local environments, depending on the electronic and spin states.711

Burden and modifications in life from the perspective of caregivers for patients after stroke

OBJECTIVE: to analyze the impact that caring has on a member of the family caring for a patient after a cerebrovascular accident, correlating life modifications and mental suffering with the perceived burden. METHOD: a cross-sectional, quantitative study, undertaken in January-April 2010 in Fortaleza, Ceará, Brazil. RESULT: 61 individuals were investigated, monitored by three hospitals' Home Care Program. Data collection was through interviews for identifying life changes, and through the application of three scales for investigating perceived burden, mental state and mental suffering. Respectively these were the Caregiver Burden Scale (CBS), the Mini-Mental State Examination (MMSE) and the Self Reported Questionnaire (SRQ). The majority of the carers were female, married, and the children of the stroke patients. The average age was 48.2 years (±12.4). The most-cited life modifications referred to the daily routine, to leisure activities, and to exhaustion or tiredness. Regarding burden, the dimensions of General tension, Isolation and Disappointment stood out. It was ascertained that overload was more severe when the carer presented more symptoms of psychological distress, in the absence of a secondary carer, and when the principal carers reported perceiving changes in their bodies and health. CONCLUSION: an association between burden and the carer's mental state was not observed. Understanding the care, through analysis of the burden and of the knowledge of the biopsychosocial situation will provide support for the nurse's work in reducing the overload for family caregivers.OBJETIVO: analizar el impacto del cuidar para el cuidador familiar de paciente después de accidente vascular cerebral, correlacionando modificaciones de vida y sufrimiento psíquico con la sobrecarga percibida. MÉTODO: estudio transversal, cuantitativo, realizado de enero a abril de 2010, en Fortaleza, Ceará, Brasil. RESULTADO: se investigaron 61 individuos, acompañados por el Programa de Servicio Domiciliar de tres hospitales. La colecta de los datos ocurrió mediante entrevista para identificar modificaciones de vida, y con la aplicación de tres escalas para investigar la sobrecarga percibida, estado mental y sufrimiento psíquico. Son ellas, respectivamente: Caregiver Burden Scale (CBS), Mini Examen del Estado Mental (MEEM) y Self Reported Questionnaire (SRQ). Los cuidadores, en su mayoría, eran del sexo femenino, casados (as) e hijo (as) de los pacientes después del AVC. Edad Media de 48,2 años (±12,4). Las modificaciones de vida más citadas fueron referentes a la rutina diaria, a las actividades de ocio y agotamiento o cansancio. En cuanto a la sobrecarga, se destacaron las dimensiones Tensión general, Aislamiento y Decepción. Se verificó mayor sobrecarga cuanto más síntomas de sufrimiento psíquico el cuidador presentase, en la ausencia de cuidador secundario y cuando los cuidadores principales relataron percibir modificación en el cuerpo y en la salud. CONCLUSIÓN: no fue observada asociación de la sobrecarga con el estado mental del cuidador. Entender la coyuntura del cuidado, mediante análisis del recargo de trabajo, y del conocimiento de la situación biopsicosocial, suministrará subsidios para la actuación del enfermero para reducir la carga generada para los cuidadores familiares.OBJETIVO: analisar o impacto do cuidar para o cuidador familiar de paciente após acidente vascular cerebral (AVC), correlacionando modificações de vida e sofrimento psíquico com a sobrecarga percebida. MÉTODO: estudo transversal, quantitativo, realizado de janeiro a abril de 2010, em Fortaleza, Ceará, Brasil. RESULTADO: investigaram-se 61 indivíduos, acompanhados pelo Programa de Atendimento Domiciliar (PAD), de três hospitais. A coleta dos dados ocorreu mediante entrevista para identificar modificações de vida, e com a aplicação de três escalas para investigar sobrecarga percebida, estado mental e sofrimento psíquico. São elas, respectivamente: Caregiver Burden Scale (CBS), Miniexame do Estado Mental (MEEM) e Self Reported Questionnaire (SRQ). Os cuidadores, na sua maioria, eram do sexo feminino, casados(as) e filho(as) dos pacientes após AVC. A média de idade era de 48,2 anos (±12,4). As modificações de vida mais citadas foram referentes à rotina diária, às atividades de lazer e esgotamento ou cansaço. Quanto à sobrecarga, destacaram-se as dimensões tensão geral, isolamento e decepção. Verificou-se maior sobrecarga quanto mais sintomas de sofrimento psíquico o cuidador apresentasse, na ausência de cuidador secundário e quando os cuidadores principais relataram perceber modificação no corpo e na saúde. CONCLUSÃO: não foi observada associação da sobrecarga com o estado mental do cuidador. Entender a conjuntura do cuidado, mediante análise da sobrecarga de trabalho, e do conhecimento da situação biopsicossocial fornecerá subsídios para a atuação do enfermeiro para reduzir a carga gerada para os cuidadores familiares

The macroecology of phylogenetically structured hummingbird-plant networks

Aim To investigate the association between species richness, species' phylogenetic signal, insularity and historical and current climate with hummingbird-plant network structure. Location 54 communities along a c. 10,000 kilometer latitudinal gradient across the Americas (39ºN - 32ºS), ranging from sea level to c. 3700 m asl, located on the mainland and on islands, and covering a wide range of climate regimes. Methods We measured null-modeled corrected complementary specialization and bipartite modularity (compartmentalization) in networks of quantitative interactions between hummingbird and plant species. Using an ordinary least squares multi-model approach, we examined the influence of species richness, phylogenetic signal, insularity, and current and historical climate conditions on network structure. Results Phylogenetically-related species, especially plants, showed a tendency to interact with a similar array of partners. The spatial variation in network structure exhibited a constant association with species' phylogeny (R2=0.18-0.19). Species richness and environmental factors showed the strongest associations with network structure (R2=0.20-0.44; R2138 =0.32-0.45, respectively). Specifically, higher levels of complementary specialization and modularity were associated to species-rich communities and communities in which closely-related hummingbirds visited distinct sets of flowering species. On the mainland, warmer temperatures and higher historical temperature stability associated to higher levels of complementary specialization. Main conclusions Previous macroecological studies of interaction networks have highlighted the importance of environment and species richness in determining network structure. Here, for the first time, we report an association between species phylogenetic signal and network structure at macroecological scale. Specifically, null model corrected complementary specialization and modularity exhibited a positive association with species richness and a negative association with hummingbird phylogenetic signal, indicating that both high richness and high inter-specific competition among closely-related 150 hummingbirds exhibit important relationships with specialization in hummingbird-plant networks. Our results document how species richness, phylogenetic signal and climate associate with network structure in complex ways at macroecological scale

Origin and Epidemiological History of HIV-1 CRF14_BG

This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Users must also make clear the license terms under which the work was published. CC BY Licence: http://creativecommons.org/licenses/by/4.0/Background: CRF14_BG isolates, originally found in Spain, are characterized by CXCR4 tropism and rapid disease progression. This study aimed to identify the origin of CRF14_BG and reconstruct its epidemiological history based on new isolates from Portugal.Methodology/Principal Findings: C2V3C3 env gene sequences were obtained from 62 samples collected in 1993–1998 from Portuguese HIV-1 patients. Full-length genomic sequences were obtained from three patients. Viral subtypes, diversity, divergence rate and positive selection were investigated by phylogenetic analysis. The molecular structure of the genomes was determined by bootscanning. A relaxed molecular clock model was used to date the origin of CRF14_BG. Geno2pheno was used to predict viral tropism. Subtype B was the most prevalent subtype (45 sequences; 73%) followed by CRF14_BG (8; 13%), G (4; 6%), F1 (2; 3%), C (2; 3%) and CRF02_AG (1; 2%). Three CRF14_BG sequences were derived from 1993 samples. Near full-length genomic sequences were strongly related to the CRF14_BG isolates from Spain. Genetic diversity of the Portuguese isolates was significantly higher than the Spanish isolates (0.044 vs 0.014, P,0.0001). The mean date of origin of the CRF14_BG cluster was estimated to be 1992 (range, 1989 and 1996) based on the subtype G genomic region and 1989 (range, 1984–1993) based on the subtype B genomic region. Most CRF14_BG strains (78.9%) were predicted to be CXCR4. Finally, up to five amino acids were under selective pressure in subtype B V3 loop whereas only one was found in the CRF14_BG cluster.Conclusions: CRF14_BG emerged in Portugal in the early 1990 s soon after the beginning of the HIV-1 epidemics, spread to Spain in late 1990 s as a consequence of IVDUs migration and then to the rest of Europe. CXCR4 tropism is a general characteristic of this CRF that may have been selected for by escape from neutralizing antibody response

X-ray emission from the Sombrero galaxy: discrete sources

We present a study of discrete X-ray sources in and around the bulge-dominated, massive Sa galaxy, Sombrero (M104), based on new and archival Chandra observations with a total exposure of ~200 ks. With a detection limit of L_X = 1E37 erg/s and a field of view covering a galactocentric radius of ~30 kpc (11.5 arcminute), 383 sources are detected. Cross-correlation with Spitler et al.'s catalogue of Sombrero globular clusters (GCs) identified from HST/ACS observations reveals 41 X-rays sources in GCs, presumably low-mass X-ray binaries (LMXBs). We quantify the differential luminosity functions (LFs) for both the detected GC and field LMXBs, whose power-low indices (~1.1 for the GC-LF and ~1.6 for field-LF) are consistent with previous studies for elliptical galaxies. With precise sky positions of the GCs without a detected X-ray source, we further quantify, through a fluctuation analysis, the GC LF at fainter luminosities down to 1E35 erg/s. The derived index rules out a faint-end slope flatter than 1.1 at a 2 sigma significance, contrary to recent findings in several elliptical galaxies and the bulge of M31. On the other hand, the 2-6 keV unresolved emission places a tight constraint on the field LF, implying a flattened index of ~1.0 below 1E37 erg/s. We also detect 101 sources in the halo of Sombrero. The presence of these sources cannot be interpreted as galactic LMXBs whose spatial distribution empirically follows the starlight. Their number is also higher than the expected number of cosmic AGNs (52+/-11 [1 sigma]) whose surface density is constrained by deep X-ray surveys. We suggest that either the cosmic X-ray background is unusually high in the direction of Sombrero, or a distinct population of X-ray sources is present in the halo of Sombrero.Comment: 11 figures, 5 tables, ApJ in pres